It is problematic in the mixing of a release agent for use between a belt and product drops that are deposited on the belt, for example product drops of a sulfuric melt, that the release agent at least partially decomposes again after some time. When a comparatively large quantity of a release agent is produced within a tank, the concentration of the release agent can thus vary over time. This could only be addressed in that the release agent is continually stirred or agitated, respectively. The correct concentration of the release agent in the case of such mixing in tanks depends exclusively on the diligence of the operator.
By way of the invention, a device and a method for pastillating a flowable product are to be improved in terms of the production of a release agent that is used between the belt and the product drops.
To this end, according to the invention, a device for pastillating a flowable product, in particular a melt, said device having a revolving belt and a drop former, is provided, wherein the drop former deposits product drops on an upper run of the steel belt, wherein the product drops in the course of transportation on the upper run of the belt solidify to form pastilles, and wherein means for wetting the belt with a liquid release agent are provided upstream of that region in which the product drops are deposited on the belt, wherein the release agent prevents or reduces the adhesion of the product drops to the belt, in which device a proportional metering pump is provided for continuously mixing the release agent from at least two liquid components during the operation of the device.
In that the release agent is continuously mixed during the operation of the device, the dwell time between the release agent being mixed and used is very minor. This offers the significant advantage that there is no risk of the components of the release agent separating again during the dwell time in a tank. In that a proportional metering pump is provided for continuously mixing the release agent it can also be ensured that the concentration or composition, respectively, of the release agent remains constant during the operation of the device. A desired composition or concentration, respectively, of the release agent herein can be set at the proportional metering pump. The composition or concentration, respectively, of the release agent is thus independent of the diligence of an operator. Since no tanks, or only small tanks, are required for intermediate storage, and in particular stirring installations are no longer required, the space and the investment required for the device for pastillating can be reduced.
In a refinement of the invention, an intermediate tank for intermediately storing the mixed release agent prior to the application to the belt is provided.
In a refinement of the invention, a holding capacity of the intermediate tank is smaller than a quantity of release agent that is required in four operating hours of the device.
The provision of a small intermediate tank which is in any case smaller than a quantity of release agent that is required in four operating hours of the device has proven advantageous. When the release agent is produced from water and from a release agent concentrate, for example, the concentrate container has to be changed from time to time. The intermediate tank then advantageously has a size which only bridges the period for changing the concentrate container. For example, the intermediate tank can also be dimensioned such that the proportional metering pump, filters, and the like can be serviced, for example cleaned, during the ongoing operation of the device for pastillating, since the release agent during the servicing period is retrieved from the intermediate tank.
In a refinement of the invention, the at least two components of the release agent in the mixed state form a dispersion.
The device according to the invention enables components of the release agent that are not mutually dissolvable and that can only be mixed to form a dispersion to be used. Since continuous mixing of the release agent is performed by the device according to the invention, there is no risk of the release agent decomposing again prior to wetting the revolving belt.
In a refinement of the invention, means for temperature controlling at least one component of the release agent are provided.
By providing means for temperature controlling, a temperature-dependent viscosity of the release agent, or of a component of the release agent, respectively, can be maintained within a desired range. On account thereof, maintaining an exact mixing ratio is significantly facilitated. Such means for temperature controlling are of great advantage in particular when mixing release agents for pastillating a sulfuric melt.
In a refinement of the invention, the proportional metering pump and a storage container for a component of the release agent are disposed in a common housing, wherein temperature control means for maintaining a temperature within the housing in a predefined range are provided.
By disposing the proportional metering pump and a storage container for a component of the release agent in a common housing, temperature controlling can be performed in a very simple and unproblematic manner by heating and/or cooling the housing interior. This is advantageous in particular in the case of aggressive release agents since no heating installations come into contact with the release agent per se.
In a refinement of the invention, means for monitoring a filling level in a storage container for a first component of the release agent are provided.
In a refinement of the invention, means for monitoring a flow and/or a flow quantity of the first component in a supply line to the proportional metering pump are provided.
In a refinement of the invention, means for monitoring a filling level of the intermediate tank having a mixed release agent are provided.
In that a plurality of filling levels and also the presence of a flow and a quantity of flow are monitored, for example, and this data is collected in a central controller, it can be ensured that no release agent or any release agent having a wrong concentration or composition is inadvertently present during the operation of the device. Should no release agent or a release agent with an erroneous composition actually be present, the device for pastillating can be rapidly switched off in order to prevent an erroneous production of pastilles.
In a refinement of the invention, the proportional metering pump is configured such that the latter is driven by means of the fluid pressure of a component of the release agent.
When a component of the release agent is water, for example, the proportional metering pump can then be driven by means of the water pressure. Except for the water pressure there is thus no external force of any kind required in order for the release agent to be continuously mixed. This significantly simplifies the design of the construction. Prior to being supplied to the proportional metering pump, the water is advantageously filtered in order to ensure that the completely mixed release agent does not contain any particles or other contaminants.
The issue on which the invention is based is also solved by a method for pastillating a flowable product, in which a liquid release agent is used between a belt and product drops that are deposited on the belt, and in which producing the liquid release agent is performed by continuously mixing at least two components of the release agent by way of a proportional metering pump, wherein a quantity of the first component of the release agent that is supplied to the proportional metering pump is determined so as to depend on a quantity of the second component that is conveyed through the proportional metering pump.
Apart from the advantages that have already been outlined in the context of the device according to the invention, the method according to the invention and especially the use of a proportional metering pump furthermore have the advantage that the concentration or composition, respectively, of the release agent is independent of variations in a supply pressure of the proportional metering pump. For example, when the release agent is mixed from a concentrate and water the proportional metering pump provides a consistent composition of the release agent even in the case of a variable water pressure.
In a refinement of the invention, monitoring and setting a temperature of the first component and/or of the second component of the release agent is provided at least in the region of the proportional metering pump.
In a refinement of the invention, heating and/or cooling of the first component of the release agent, of the second component of the release agent, and/or of the proportional metering pump is provided.
In a refinement of the invention, disposing a storage container for at least one component of the release agent and of the proportional metering pump in a common housing, and monitoring and setting a temperature in the housing are provided.
Further features and advantages of the invention are derived from the claims and from the following description of preferred embodiments of the invention in conjunction with the drawings. Individual features of the various embodiments in the various drawings herein can be combined with one another in any arbitrary manner without departing from the scope of the invention.